.The Flobert cartridge was developed by the inventor of breech action firearm, Mr Flobert of Belgium in the mid 1800'sIt was known as "The Garden Shotgun" and made by many manufacturers in the early to mid 1900's for short-range shooting of small rodents.Winchester introduced their version, the "Winchester Model 36 Shotgun" in 1920 and only made 20,306 guns; the firearm was discontinuedin 1927 and Winchester stopped production of the cartridge some time shortly after 1927.Again, there are many different 9mm rim-fire shotguns in the U.S. and all should be able to use these cartridges, but as with any firearm it isup to the owner to make sure the firearm is in good working order before using it.These cartridges are 1.439" or 36.56mm long, the rim is .406" or 10.33mm in diameter, the case base diameter above the rim is .342" or8.7mm in diameter, and the top of the case is .326" or8.3mm in diameter.